1. Introduction

Domain Name System (DNS) records may be updated using DNS Update [RFC2136]. Other mechanisms such as a Discovery Proxy [RFC8766] can also generate changes to a DNS zone. This document specifies a protocol for DNS clients to subscribe to receive asynchronous notifications of changes to RRsets of interest. It is immediately relevant in the case of DNS-based Service Discovery [RFC6763] but is not limited to that use case; it provides a general DNS mechanism for DNS record change notifications. Familiarity with the DNS protocol and DNS packet formats is assumed [RFC1034] [RFC1035] [RFC6895].